1. Field of the Invention
The present invention relates to a sheet conveyance apparatus conveying sheets by using a conveyance roller while suppressing meandering of the sheets, and to a printing apparatus performing printing on sheets.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2007-225947 discusses a printing apparatus in which there are provided in a paper path route for a roll of paper a pair of right and left regulating guides preventing meandering. The right and left guides are moved so as to make the distance between the guides, which regulate the positions of the right and left side ends of the roll paper, smaller than the width of the roll paper to thereby rectify the attitude of the roll paper, and then the guides are moved to positions corresponding to the width of the roll paper, thereby making it possible to prevent meandering of the roll paper.
In the apparatus discussed in Japanese Patent Application Laid-Open No. 2007-225947, conveyance rollers are provided on the upstream and downstream sides of the paper width guide to sandwich and convey a roll of paper. And, when performing meandering rectification, the press contact of the conveyance rollers is released, and the paper roll end portions are further pushed beyond the paper width by a guide unit. Besides, the position of the guide unit is controlled to move according to the width dimension of the roll paper input to the apparatus beforehand.
When conveyance is performed while effecting positional regulation on the side end portions of the continuous paper paid out of the roll by means of the paper width guide, twisting is generated in the portion of the continuous paper between the paper width guide and the upstream side conveyance roller or between the paper width guide and the downstream side conveyance roller, resulting in partial paper uplift or creases. Further, depending upon the position of the paper width guide, the paper width guide presses the continuous paper in the width direction, so that the sheet is placed in a swollen state. If the continuous paper is held in this state by the downstream side conveyance roller, creases will be generated.
Further, to improve the conveyance precision for the roll paper and to suppress damage of the roll paper due to the pressure by the conveyance rollers, it is necessary for the conveyance rollers to apply pressure uniformly onto the paper. As an advantageous construction in terms of cost and size in uniformly applying pressure, a roller opposed to the conveyance rollers and driven to rotate may be divided in the paper width direction.
However, it is rather difficult to arrange the respective rotation shafts of the divided driven rollers to be parallel with high precision, relative to the rotation shafts of the conveyance rollers. If the rotation shafts of the adjacent driven rollers are inclined and the continuous paper is huddled during conveyance, creases and jamming are generated.